In printers, in particular, high speed printers printing on continuous rolls of material, a sensor arrangement is used to check the quality of the printed indicia on the material. For example, light emitting elements in the sensor arrangement transmit light to the printed material as the printed material is transported along a path under, typically orthogonal to, the sensor arrangement. The transmitted light is reflected of the printed material upward to a lens in the sensor arrangement. After passing through the lens, the reflected light, which includes data regarding the printed indicia, is analyzed by the sensor arrangement to evaluate the quality of the printed indicia, for example, to check for registration errors.
Typically, the sensor arrangement is quite close to the material as the material is transported along the path as high speeds. The transport of the printed material causes detritus, such as dust from the material and ink solids, to be dispersed toward and into the sensor arrangement. The detritus can adhere to the light emitting elements and/or lens causing the sensor arrangement to interpret the detritus deposits as errors in the printed indicia. If the perceived errors are sufficiently large, the sensor arrangement can issue a warning that the quality of the printed indicia has been compromised or may even initiate automatic shut-down procedures. The warning and shut-downs can increase down time. Further, to remove the detritus from the sensor arrangement, it is typically necessary to employ trained service personnel, rather than users of the printer, to partially dissemble the sensor arrangement to access the components that must be cleaned. Employing trained personnel instead of users, increases down time and costs associated with operating the printer.